101. 102. 103. 104. 105. 10-17. 10-16. 10-15. 10-14. Closed loop. Open loop. O v erlap pin g A llan D ev ... UWA, School of Physics. 35, Stirling Hwy, Crawley,.
High performance frequency dissemination for metrology applications with optical fibers.
the development of fiber based distribution system for the Nasa Deep Space Network [1-3]. The astronomy community has demonstrated high performance fiber frequency distribution both for VLBI applications [4] and for modern telescope synchronization like the Atacama Large
Abstract—In this paper we describe the recent progress in the development of a high performance fiber based frequency distribution system for metrology applications. The fiber link operates at 100 MHz and 1 GHz and uses a standard telecom fiber of the Paris metropolitan network to disseminate the LNE-SYRTE frequency references over 44 km to the Laboratoire de Physique des Laser (LPL). Preliminary results of a 88 km compensated optical link is also presented.
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M.E. Tobar UWA, School of Physics 35, Stirling Hwy, Crawley, Western Australia.
C. Daussy, O. Lopez, A. Amy-Klein, Ch. Chardonnet, LPL, Univ.Paris 13 99, Av. Jean-Baptiste Clément, Villetaneuse, France.
G. Santarelli, F. Narbonneau, M. Lours, D. Chambon, S. Bize and A. Clairon. LNE-SYRTE, Obsevatoire de Paris 61, Av. de l’Observatoire, Paris, France
INTRODUCTION
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Ultra-stable frequency sources play an important role in many modern metrology and fundamental physics applications. Very high sensitivity is required in many cases and thus, low noise and ultra stable oscillators and clocks are employed in for VLBI measurements, for the tests of Einstein's relativity, or for navigation. The opportunity of comparing clocks, even when the laboratories are separated by 100 km, could greatly help their accuracy evaluation. The objective is then to distribute frequency standards, without degradation of the metrological properties. From the late eighties, the Jet Propulsion Laboratory has paved the way of
Figure 2
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Frequency stability of the CO2/OsO4 optical frequency standard at the LPL compared to the LNE-SYRTE cryogenic sapphire oscillator via the 100 MHz optical link and a femtosecond comb optical synthesizer.
Microwave Array (ALMA). More recently the National Institute for Standard and Tecnology (NIST) have been connected with JILA using high performance optical link [5].
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Frequency stability of the 44 km optical link between the LNE-SYRTE and the LPL operating at 100 MHz (circles: open loop frequency stability, diamonds: closed loop frequency stability).
0-7803-9052-0/05/$20.00 © 2005 IEEE.
THE 100 MHZ DISTRIBUTION SYSTEM
In the past two years, we have developed a compensated fiber distribution system operating at 100 MHz with a shortterm frequency stability of 1.5x10-14 at one second and 1x10-17 at one day integration time over 44 Km telecom optical fiber Fig1. We use this link to compare a Cryogenic
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and the LPL. An electronic system developed at the LNESYRTE (Fig. 4) compensates phase fluctuations introduced along the link by external perturbations (temperature variations, mechanical vibrations). The long-term frequency stability is presently limited to about 10-16 by stray optical reflections. Moreover, the signal-to-noise ratio is degraded by Brillouin back-scattering (SBS). To overcome these limitations, optical filters based on fibre Bragg grating will be added to the system to reduce by 30-40dB, all parasitic terms. In this configuration, we expect to reach both shortterm (3x10-15 at 1s) and long-term frequency stability, (
